LeetCode: Contains Duplicate II Solution

Approach

Use hash table to store the latest index for num

This make sure i - j will always be positive and smallest at the iterating time

Implementation

1var containsNearbyDuplicate = function (nums, k) {
2  const map = {}
3
4  for (const [i, num] of nums.entries()) {
5    const j = map[num]
6    if (j !== undefined && i - j <= k) {
7      return true
8    }
9
10    map[num] = i
11  }
12
13  return false
14}

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